Abstract: To quantify the effects of hydro-meteorological forecasting error on the reservoir real time operation, the Three Gorges Reservoir is taken as object. Based on the analysis results of the error of the historical forecasting data, the assumed inflow process is used as the input of the flood regulation calculation model, in which the inflow process is superimposed with the corresponding forecasting error of different probability. The reservoir level targets below the risk control point under different forecast period and error assurance rate were analyzed, based on the analysis, the risk control strategy for real-time operation of Three Gorges Reservoir is proposed. The research could provide reference for scientific operation of reservoirs.